1. Field of the Invention
The present invention relates to a mobile communication terminal, and more particularly to a hinge structure for connecting a pair of housings of a mobile communication terminal to be folded or opened.
2. Description of the Related Art
Mobile communication terminals are generally classified into bar, flip, and folder types according to their external forms. A bar type has a single body housing provided with the data input/output devices and the voice transmission and reception devices, and a flip type is made by adding a flip to the bar type. A bar type terminal has a keypad exposed to cause erroneous operation due to its being inadvertently pressed, while a flip type terminal has a keypad protected by the flip from inadvertent pressing. However, both bar and flip type terminals have a common limitation in miniaturization because distance between a transmission port and a reception port may not be reduced below a certain limit.
On the other hand, a folder type terminal includes a folder connected by a hinge to a main body so the folder may be turned to open or close the main body. The folder is folded onto the main body to prevent the keypad from inadvertent operation in the standby mode, while it is turned away from the main body in the communication mode to make the distance between the transmission and the reception port sufficient for adapting to the mouth and ear, thus facilitating miniaturization of the terminal. This feature has contributed to the popularity of the folder type terminal.
Meanwhile, the hinge structure for connecting the main body and the folder may be designed to provide a drive force to automatically or semi-automatically swing the folder. An example of a hinge structure to semi-automatically swing the folder is disclosed in U.S. Pat. No. 6,292,980, issued Sep. 25, 2001, and commonly assigned to the assignee of the present application. Such a hinge structure includes a pair of cams pushed toward each other by a resilient force, so ridges of one cam rotate and engage valleys of the other cam to produce a drive force for folding or opening the folder onto or off the main body according to the rotational angle of the folder. This semiautomatic hinge structure is simple in construction, but suffers a drawback that the user must directly turn the folder in order to open or close the terminal.
On the contrary, an automatic hinge structure employs a motor that is driven by a simple switching operation to open or close the folder. Although this provides a user with an easy means to handle the folder, the structure is complicated by the motor and the necessary conductor lines arranged to supply a power or a control signal to the motor, thus making it difficult to miniaturize the terminal, increasing the production cost and the power consumption of the terminal.